376 ZOOLOGY 



stand not only at the head of their own phylum, but in front 

 of all other animals, man alone excepted. It is not a very 

 large order, only about 25,000 species are described. All of 

 these are terrestrial, and most of them inhabit the warmer and 

 more temperate parts of the globe. 



The head is freely moveable, the eyes large and prominent, 

 and, as is often the case in insects, they are larger in the male 

 than in the female. There are three ocelli. The antennae 

 are often crooked, and then consist of a basal joint or shaft, 

 and ten to twelve shorter joints ; they may be straight. 



The mouth is adapted for biting or licking; there is a 

 small labrum, and the mandibles are large and stout. The 

 maxillae and labium are elongated, palps being present in 

 each case. The nectar upon which bees feed is licked up by 

 the ligula, and deposited upon a sheath formed of the labial 

 palps and maxOlae, and in the sheath thus formed the food 

 passes up to the mouth. The ligula is the front edge of the 

 labium. In bees it is enormously developed, and divided 

 into three lobes, the two outer of these are termed paraglossae. 



On the mesothorax are two small scales known as the 

 tegulae, covering the base of the wings. 



The legs have a five-jointed tarsus, and in bees the tibia 

 and tarsus, especially those of the posterior pair of legs, are 

 covered with short hairs, these help to collect and convey 

 home the pollen grains the bees have gathered during their 

 frequent visits to flowers. 



The abdomen is as a rule pedunculated, the two anterior 

 segments forming the peduncle. In the female the abdomen 

 ends in an ovipositor, which in the Aculeata is modified and 

 forms a sting. This complicated apparatus developes from 

 six protuberances on the embryo, -four on the last but one, and 

 two on the last segment. These protuberances elongate and 

 form a grooved process with two stylets and a pair of lateral 

 sheaths, besides these there are certain supporting plates. 

 The poison consists of formic acid with some fatty sub- 

 stances ; it is secreted in a special gland, which communicates 

 with a reservoir, this opens at the base of the grooved 

 process. 



The nervous system consists of an unusually large and 



